The present invention relates to a cap for a rotary cell of a top roller.
In a top roller having a rotary cell rotatably attached by a needle or balls to each end of an arbor, a cap is provided at the end portion of each rotary cell to prevent entry of fibers or dust which may make rotation of the rotary cells impossible, and to prevent leakage of lubricant such as grease.
However, this cap is provided at the center with an oil supply hole which is always open, so that injected lubricant flows backward through the hole. This cap is also defective in that fibers or dust enters through the oil supply hole. Furthermore, since the oil supply hole projects inwardly by a considerable length to reduce the backward flow of the injected lubricant, the center of a rotary portion consisting of a needle or balls is offset relative to the center of the rotary cell. As a consequence, uneven rotation of the rotary cell will readily occur, which is a further defect of the conventional cap.